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MicroK8sの独習3 〜Redisを使用したPHPのゲストブックアプリケーションのデプロイ〜

もう面倒やから4台クラスタ状態をスナップショットとっとく

$ seq 4 | xargs -I{} -P4 -n1 lxc launch mk8s mk8s{};seq 4 | xargs -I{} -P4 -n1 lxc exec mk8s{} -- microk8s status | grep nodes;for i in $(seq 2 4) ; do lxc exec mk8s1 -- microk8s add-node | tail -n1 | xargs lxc exec mk8s$i -- ; done
Creating mk8s4
Creating mk8s3
Creating mk8s1
Creating mk8s2
Starting mk8s1
Starting mk8s3
Starting mk8s4
Starting mk8s2
Contacting cluster at 10.116.214.195
Waiting for this node to finish joining the cluster. ..
Contacting cluster at 10.116.214.195
Waiting for this node to finish joining the cluster. ..
Contacting cluster at 10.116.214.195
Waiting for this node to finish joining the cluster. ..
$ kubectl get nodes
NAME    STATUS   ROLES    AGE     VERSION
mk8s3   Ready    <none>   13m     v1.20.5-34+40f5951bd9888a
mk8s4   Ready    <none>   12m     v1.20.5-34+40f5951bd9888a
mk8s1   Ready    <none>   3d22h   v1.20.5-34+40f5951bd9888a
mk8s2   Ready    <none>   15m     v1.20.5-34+40f5951bd9888a
$ tmux save-buffer - | xsel --clipboard                                                                                                                                           
$ lxc snapshot mk8s1                                                                                                                                                              
$ lxc snapshot mk8s2                                                                                                                                                              
$ lxc snapshot mk8s3                                                                                                                                                              
$ lxc snapshot mk8s4
$ lxc list
+-------+---------+-----------------------------+----------------------------------------------+-----------+-----------+
| NAME  |  STATE  |            IPV4             |                     IPV6                     |   TYPE    | SNAPSHOTS |
+-------+---------+-----------------------------+----------------------------------------------+-----------+-----------+
| mk8s1 | RUNNING | 10.116.214.195 (eth0)       | fd42:d878:2ae:7d9e:216:3eff:fe81:8105 (eth0) | CONTAINER | 1         |
|       |         | 10.1.238.128 (vxlan.calico) |                                              |           |           |
+-------+---------+-----------------------------+----------------------------------------------+-----------+-----------+
| mk8s2 | RUNNING | 10.116.214.109 (eth0)       | fd42:d878:2ae:7d9e:216:3eff:fee1:134f (eth0) | CONTAINER | 1         |
|       |         | 10.1.115.128 (vxlan.calico) |                                              |           |           |
+-------+---------+-----------------------------+----------------------------------------------+-----------+-----------+
| mk8s3 | RUNNING | 10.116.214.130 (eth0)       | fd42:d878:2ae:7d9e:216:3eff:feac:3825 (eth0) | CONTAINER | 1         |
|       |         | 10.1.217.192 (vxlan.calico) |                                              |           |           |
+-------+---------+-----------------------------+----------------------------------------------+-----------+-----------+
| mk8s4 | RUNNING | 10.116.214.113 (eth0)       | fd42:d878:2ae:7d9e:216:3eff:fe59:af6d (eth0) | CONTAINER | 1         |
|       |         | 10.1.236.128 (vxlan.calico) |                                              |           |           |
+-------+---------+-----------------------------+----------------------------------------------+-----------+-----------+

マスターノードの作成

$ kubectl apply -f https://raw.githubusercontent.com/kubernetes/website/master/content/ja/examples/application/guestbook/redis-master-deployment.yaml
deployment.apps/redis-master created
$ kubectl get deploy
NAME           READY   UP-TO-DATE   AVAILABLE   AGE
redis-master   1/1     1            1           87s
$ kubectl apply -f https://raw.githubusercontent.com/kubernetes/website/master/content/ja/examples/application/guestbook/redis-master-service.yaml
service/redis-master created
$ kubectl get service
NAME           TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)    AGE
kubernetes     ClusterIP   10.152.183.1    <none>        443/TCP    3d22h
redis-master   ClusterIP   10.152.183.42   <none>        6379/TCP   10s

スレーブ作成

$ kubectl apply -f https://raw.githubusercontent.com/kubernetes/website/master/content/ja/examples/application/guestbook/redis-slave-deployment.yaml
deployment.apps/redis-slave created
$ kubectl get deploy
NAME           READY   UP-TO-DATE   AVAILABLE   AGE
redis-master   1/1     1            1           6m
redis-slave    2/2     2            2           2m13s
$ kubectl apply -f https://raw.githubusercontent.com/kubernetes/website/master/content/ja/examples/application/guestbook/redis-slave-service.yaml
service/redis-slave created
$ kubectl get services
NAME           TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)    AGE
kubernetes     ClusterIP   10.152.183.1     <none>        443/TCP    3d22h
redis-master   ClusterIP   10.152.183.42    <none>        6379/TCP   5m16s
redis-slave    ClusterIP   10.152.183.246   <none>        6379/TCP   12s

フロントエンド作成

$ kubectl apply -f https://raw.githubusercontent.com/kubernetes/website/master/content/ja/examples/application/guestbook/frontend-deployment.yaml
deployment.apps/frontend created
$ kubectl get pods -l app=guestbook
NAME                        READY   STATUS    RESTARTS   AGE
frontend-6c6d6dfd4d-q4gqh   1/1     Running   0          73m
frontend-6c6d6dfd4d-g8vlj   1/1     Running   0          73m
frontend-6c6d6dfd4d-7qgkw   1/1     Running   0          73m
$ kubectl apply -f https://raw.githubusercontent.com/kubernetes/website/master/content/ja/examples/application/guestbook/frontend-service.yaml
service/frontend created
$ kubectl get services
NAME           TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE
kubernetes     ClusterIP   10.152.183.1     <none>        443/TCP        4d
redis-master   ClusterIP   10.152.183.42    <none>        6379/TCP       76m
redis-slave    ClusterIP   10.152.183.246   <none>        6379/TCP       71m
frontend       NodePort    10.152.183.60    <none>        80:30020/TCP   7s

やり直したけどやっぱりフロントエンドの画面がエラーで動かないと思ってyamlのdiffとったら
差分出てる。。。

$ diff <(wget -O - -q https://k8s.io/examples/application/guestbook/frontend-deployment.yaml) <(wget -O - -q https://raw.githubusercontent.com/kubernetes/website/master/content/ja/examples/application/guestbook/frontend-deployment.yaml)
1c1
< apiVersion: apps/v1
---
> apiVersion: apps/v1 # for versions before 1.9.0 use apps/v1beta2
6,7c6
<     app.kubernetes.io/name: guestbook
<     app.kubernetes.io/component: frontend
---
>     app: guestbook
11,12c10,11
<       app.kubernetes.io/name: guestbook
<       app.kubernetes.io/component: frontend
---
>       app: guestbook
>       tier: frontend
17,18c16,17
<         app.kubernetes.io/name: guestbook
<         app.kubernetes.io/component: frontend
---
>         app: guestbook
>         tier: frontend
21,23c20,21
<       - name: guestbook
<         image: paulczar/gb-frontend:v5
<         # image: gcr.io/google-samples/gb-frontend:v4
---
>       - name: php-redis
>         image: gcr.io/google-samples/gb-frontend:v4
30a29,36
>           # Using `GET_HOSTS_FROM=dns` requires your cluster to
>           # provide a dns service. As of Kubernetes 1.3, DNS is a built-in
>           # service launched automatically. However, if the cluster you are using
>           # does not have a built-in DNS service, you can instead
>           # access an environment variable to find the master
>           # service's host. To do so, comment out the 'value: dns' line above, and
>           # uncomment the line below:
>           # value: env

よしスナップショットから復旧や!

$ lxc stop mk8s{1,2,3,4}
$ seq 4 | xargs -n1 -P4 -I{} lxc restore mk8s{} snap0
$ lxc start mk8s{1,2,3,4}
$ kubectl get nodes
NAME    STATUS   ROLES    AGE    VERSION
mk8s2   Ready    <none>   124m   v1.20.5-34+40f5951bd9888a
mk8s1   Ready    <none>   4d     v1.20.5-34+40f5951bd9888a
mk8s3   Ready    <none>   122m   v1.20.5-34+40f5951bd9888a
mk8s4   Ready    <none>   121m   v1.20.5-34+40f5951bd9888a
$ kubectl get pods -A
NAMESPACE     NAME                                      READY   STATUS    RESTARTS   AGE
kube-system   calico-node-bm2kb                         1/1     Running   1          124m
kube-system   calico-node-m2k78                         1/1     Running   1          123m
kube-system   calico-node-rmbsc                         1/1     Running   1          121m
kube-system   calico-node-rs879                         1/1     Running   1          126m
kube-system   calico-kube-controllers-847c8c99d-5tcwh   1/1     Running   2          4d

OK便利便利

とりあえず落ち着いてMongoDB版で試してみよう
話はそれからだ

まずはMongoDB立てる

$ kubectl apply -f https://k8s.io/examples/application/guestbook/mongo-deployment.yaml
deployment.apps/mongo created
$ kubectl get deployment/mongo
NAME    READY   UP-TO-DATE   AVAILABLE   AGE
mongo   1/1     1            1           47s

MongoDB用のサービス起動

$ kubectl apply -f https://k8s.io/examples/application/guestbook/mongo-service.yaml
service/mongo created
$ kubectl get service
NAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)     AGE
kubernetes   ClusterIP   10.152.183.1     <none>        443/TCP     4d
mongo        ClusterIP   10.152.183.208   <none>        27017/TCP   5s

フロントエンド起動

$ kubectl apply -f https://k8s.io/examples/application/guestbook/frontend-deployment.yaml
deployment.apps/frontend created
$ kubectl get pods -l app.kubernetes.io/name=guestbook -l app.kubernetes.io/component=frontend
NAME                       READY   STATUS    RESTARTS   AGE
frontend-848d88c7c-qc7nx   1/1     Running   0          4m5s
frontend-848d88c7c-pg2gb   1/1     Running   0          4m5s
frontend-848d88c7c-dj96j   1/1     Running   0          4m5s

フロントエンドのサービス起動

$ kubectl apply -f https://k8s.io/examples/application/guestbook/frontend-service.yaml
service/frontend created
$ kubectl get service
NAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)     AGE
kubernetes   ClusterIP   10.152.183.1     <none>        443/TCP     4d
mongo        ClusterIP   10.152.183.208   <none>        27017/TCP   6m50s
frontend     ClusterIP   10.152.183.53    <none>        80/TCP      8s

ココらへんまで大体redisと同じ流れやねマスタースレーブが無くなった感じか

だめや画面出たけどmongodbつながらないみたいなエラー出るぞ

英語がわからん
これってようはk8sクラスター内のネットワークからしかアクセスできない?

Creating the Frontend Service

The mongo Services you applied is only accessible within the Kubernetes cluster because the default type for a Service is ClusterIP. ClusterIP provides a single IP address for the set of Pods the Service is pointing to. This IP address is accessible only within the cluster.

If you want guests to be able to access your guestbook, you must configure the frontend Service to be externally visible, so a client can request the Service from outside the Kubernetes cluster. However a Kubernetes user you can use kubectl port-forward to access the service even though it uses a ClusterIP.

う〜んフロントエンドからバックエンドへの通信がうまく動いてないっぽいけどこれはどっからどこに通信走ってんだ。。
ブラウザから直接mongo行こうとしてるならつながらないのはなんとなくわかるけどフロントエンドサーバからmongo行ってるなら内部の通信が問題な気がするし。。。

これ多分内部で名前解決出来てないわ。。。

$ lxc exec mk8s1 -- kubectl exec -it frontend-848d88c7c-6cnh8 bash
kubectl exec [POD] [COMMAND] is DEPRECATED and will be removed in a future version. Use kubectl exec [POD] -- [COMMAND] instead.
root@frontend-848d88c7c-6cnh8:/var/www/html# cat 
controllers.js  guestbook.php   index.html      
root@frontend-848d88c7c-6cnh8:/var/www/html# grep mongo guestbook.php 
// echo extension_loaded("mongodb") ? "loaded\n" : "not loaded\n";
  $host = 'mongo';
  $mongo_host = "mongodb+srv://$host/guestbook?retryWrites=true&w=majority";
    $manager = new MongoDB\Driver\Manager("mongodb://$host");
      echo '{"error": "An error occured connecting to mongo ' . $host . '"}';
    $host = 'mongo';
    $manager = new MongoDB\Driver\Manager("mongodb://$host");
      echo '{"error": "An error occured connecting to mongo ' . $host . '"}';
root@frontend-848d88c7c-6cnh8:/var/www/html# 

てことはDNS周りやな多分microk8sのアドオンにありそう

$ microk8s status | grep dns
    dns                  # CoreDNS
$ microk8s enable dns
Enabling DNS
Applying manifest
serviceaccount/coredns created
configmap/coredns created
deployment.apps/coredns created
service/kube-dns created
clusterrole.rbac.authorization.k8s.io/coredns created
clusterrolebinding.rbac.authorization.k8s.io/coredns created
Restarting kubelet
Adding argument --cluster-domain to nodes.
Configuring node 10.116.214.130
Configuring node 10.116.214.113
Configuring node 10.116.214.109
Configuring node 10.116.214.195
Adding argument --cluster-dns to nodes.
Configuring node 10.116.214.130
Configuring node 10.116.214.113
Configuring node 10.116.214.109
Configuring node 10.116.214.195
Restarting nodes.
Configuring node 10.116.214.130
Configuring node 10.116.214.113
Configuring node 10.116.214.109
Configuring node 10.116.214.195
DNS is enabled

これで行けたかと思ったけどだめだった

podがまだdns認識出来てないんじゃないかな。。。
とりあえずクラスタ一回全部落として再起動したらどうやろか
フロントエンドも3つも立ち上げたら時間かかりそうやし2個に落として再起動しよう

$ kubectl scale deployment frontend --replicas=2
$ lxc stop mk8s{1,2,3,4}; lxc start mk8s{1,2,3,4}
$ seq 4 | xargs -I{} -P4 -n1 lxc exec mk8s{} -- microk8s status | grep nodes
  datastore master nodes: 10.116.214.195:19001 10.116.214.109:19001 10.116.214.130:19001
  datastore standby nodes: 10.116.214.113:19001
  datastore master nodes: 10.116.214.195:19001 10.116.214.109:19001 10.116.214.130:19001
  datastore standby nodes: 10.116.214.113:19001
  datastore master nodes: 10.116.214.195:19001 10.116.214.109:19001 10.116.214.130:19001
  datastore standby nodes: 10.116.214.113:19001
  datastore master nodes: 10.116.214.195:19001 10.116.214.109:19001 10.116.214.130:19001
  datastore standby nodes: 10.116.214.113:19001
$ kubectl get pods
NAME                       READY   STATUS    RESTARTS   AGE
frontend-848d88c7c-9lpc4   1/1     Running   1          9m35s
frontend-848d88c7c-6cnh8   1/1     Running   1          11m
mongo-75f59d57f4-mtqq2     1/1     Running   1          127m

んでプロキシつかって8080で外部に晒すと。。。

$ lxc list mk8s1
+-------+---------+-----------------------------+----------------------------------------------+-----------+-----------+
| NAME  |  STATE  |            IPV4             |                     IPV6                     |   TYPE    | SNAPSHOTS |
+-------+---------+-----------------------------+----------------------------------------------+-----------+-----------+
| mk8s1 | RUNNING | 10.116.214.195 (eth0)       | fd42:d878:2ae:7d9e:216:3eff:fe81:8105 (eth0) | CONTAINER | 1         |
|       |         | 10.1.238.128 (vxlan.calico) |                                              |           |           |
+-------+---------+-----------------------------+----------------------------------------------+-----------+-----------+
$ kubectl port-forward svc/frontend --address 0.0.0.0 8080:80
Forwarding from 0.0.0.0:8080 -> 80

いけたーー!
ソースみたらなんとなくバックエンドからmongoって名前で名前解決失敗してそうってのがわかったから良かったけどあれ無かったら迷宮入りやぞこれ

とりあえずkubectl port-forwardだとmk8s1に8080でアクセスするしかできなくなるからmetalLB有効にしてロードバランサ設定でIP降った方がええねこれ

てかリダイスのチュートリアル閉じとけよ。。。
流石に罠すぎんだろ。。。

とりあえずここまで忘れないように2〜3を記事化して閉じよう

このスクラップは2021/04/20にクローズされました
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